JP5478455B2 - Network apparatus and mobile station control method - Google Patents

Description

  The present invention relates to a network device, a base station, and a mobile station control method for controlling transition of mobile stations connectable to a plurality of wireless communication systems.

  A mobile station that can be connected to a plurality of wireless communication systems such as a 3G (Wideband-CDMA) system (hereinafter referred to as 3G) and a Long Term Evolution system (hereinafter referred to as LTE). Inter-RAT mobility) is defined in various ways.

  For example, when a mobile station located in LTE transmits a CS call connection request using a circuit switched network (CS domain), the mobile station executes a fallback (CSFB) to 3G CS domain, It is defined that the call processing is executed in the fallback 3G (see Non-Patent Document 1).

  In recent years, the number of small base stations (for example, HeNB) such as femtocells that mobile users install at home is increasing (for example, see Non-Patent Document 2).

  When such a small base station constitutes a CSG (Closed Subscriber Group) / Hybrid cell that can be accessed only by a mobile station permitted in advance, the mobile station to which the right to access the CSG / Hybrid cell is given It is possible to autonomously search the CSG / Hybrid cell and execute a handover to the CSG / Hybrid cell.

3GPP TS 24.301, Technical Specification Group Core Network and Terminals; Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 3GPP TS 22.220, Service requirements for Home NodeBs (UMTS) and Home eNodeBs (LTE)

  By the way, from the viewpoint of traffic distribution, so-called open type cells that can be accessed by an unspecified number of mobile stations such as macro cells formed by general base stations for public communications installed by mobile communication carriers. In some cases, it is desired to move the mobile station to the macro cell.

  Also, even when the mobile station does not autonomously have a CSG / Hybrid cell search function, the mobile station is transitioned to a specific CSG / Hybrid cell, and a specific communication service is provided in the destination CSG / Hybrid cell. It is possible.

  In order to manage the mobility of such mobile stations, the neighbor cell information table (NRT) of the mobile station is managed in network devices such as RNC (Radio Network Controller) and SGSN (Serving GPRS Support Node). There is a need to.

  However, the neighboring cell information table has an enormous number of cells included in the neighboring cell information table in areas where small cells formed by small base stations that can be freely installed by users (such as housing complexes) There is a problem in that the processing load on the network device increases significantly.

  Therefore, the present invention provides a network device that realizes transition of a mobile station to a neighboring cell while suppressing an increase in processing load related to the neighboring cell information table even when there are a large number of base stations in the vicinity of the mobile station, An object is to provide a base station and a mobile station control method.

  A first feature of the present invention is that a mobile station connectable to at least one of a first radio communication system (LTE system 10) and a second radio communication system (3G system 20) different from the first radio communication system. (Mobile station 301) is a network device (RNC 210) for controlling mobility, and the neighbor cell information table (NRT500) based on the mobile station transitioning from the first radio communication system to the second radio communication system ) To store information on neighboring cells of the mobile station (NRT storage unit 211), and based on the neighboring cell information stored in the neighboring cell information table, the mobile station transmits the second wireless communication to the mobile station. A mobile station control unit (mobile station control unit 213) that performs mobility control from the system to the first wireless communication system, and the storage unit is configured to store a neighbor cell of the mobile station from the neighbor cell information table. And gist storing a trigger to erase information.

  In the above-described feature of the present invention, the storage unit may include at least an effective time of the neighboring cell or an effective area where application of the information of the neighboring cell is effective as the information on the neighboring cell.

  In the above-described feature of the present invention, the storage unit stores the neighbor of the mobile station from the neighbor cell information table when a predetermined time has elapsed after storing the neighbor cell information of the mobile station in the neighbor cell information table. The cell information may be erased.

  A second feature of the present invention is a base station that controls mobility of a mobile station connectable to at least one of a first wireless communication system and a second wireless communication system different from the first wireless communication system. A storage unit for storing information on neighboring cells of the mobile station in a neighboring cell information table based on a transition of the mobile station from the first wireless communication system to the second wireless communication system; and the neighboring cell information A mobile station controller configured to perform mobility control of the mobile station from the second radio communication system to the first radio communication system based on information on the neighboring cells stored in a table, The gist is to store a trigger for erasing information on neighboring cells of the mobile station from the neighboring cell information table.

  A third feature of the present invention is a mobile station control method for controlling mobility of a mobile station connectable to at least one of a first radio communication system and a second radio communication system different from the first radio communication system. And storing the neighboring cell information of the mobile station in a neighboring cell information table based on the mobile station transitioning from the first wireless communication system to the second wireless communication system; A step of performing movement control of the mobile station from the second radio communication system to the first radio communication system based on the information of the neighbor cell stored in the information table; and the movement from the neighbor cell information table And a step of storing a trigger for erasing information of neighboring cells of the station.

  According to the features of the present invention, even when a large number of base stations exist in the vicinity of a mobile station, a network that realizes transition of the mobile station to a neighboring cell while suppressing an increase in processing load related to the neighboring cell information table An apparatus, a base station, and a mobile station control method can be provided.

1 is an overall schematic configuration diagram of a wireless communication system according to an embodiment of the present invention. It is a functional block structure of RNC210 which concerns on embodiment of this invention. It is a figure which shows the communication sequence of the radio | wireless communications system which concerns on embodiment of this invention. It is a figure which shows an example of NRT500 which concerns on embodiment of this invention.

  Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) Overall Schematic Configuration of Radio Communication System FIG. 1 is an overall schematic configuration diagram of a radio communication system according to the present embodiment. As shown in FIG. 1, the radio communication system according to this embodiment includes an LTE system 10 and a 3G system 20.

  The LTE system 10 is a radio communication system according to the LTE scheme. The 3G system 20 is a wireless communication system according to the 3G system (W-CDMA). That is, the LTE system 10 and the 3G system 20 use different radio communication technologies (RAT).

  The LTE system 10 (first wireless communication system) includes an LTE core network 11, HeNBs 111 to 113, and an MME 120 (Mobility Management Entity). The 3G system 20 (second wireless communication system) includes a 3G core network 21, an RNC 210, a BTS 220, and an SGSN 230 (Serving GPRS Support Node).

  The mobile stations 301 and 302 can be connected to the LTE system 10 and the 3G system 20 by radio. Specifically, the mobile stations 301 and 302 perform radio communication with the HeNBs 111 to 113 and connect to the LTE system 10. In addition, the mobile stations 301 and 302 perform wireless communication with the BTS 220 and connect to the 3G system 20.

  The HeNBs 111 to 113 are small base stations that can be installed by users of the mobile stations 301 and 302, and form cells C11 to C13, respectively. The BTS 220 is a general base station for public communication installed by a mobile communication carrier, and forms a macro cell C1.

(2) Functional Block Configuration of Radio Communication System Next, among the devices configuring the radio communication system described above, in this embodiment, a network device that controls the transition between the LTE systems 10 to 3G system 20 of the mobile stations 301 and 302 is illustrated. A functional block configuration of the RNC 210 to be configured will be described.

  FIG. 2 is a functional block configuration of the RNC 210. As shown in FIG. 2, the RNC 210 includes an NRT storage unit 211, a mobile station control unit 213, and a notification unit 215.

  The NRT storage unit 211 stores a neighboring cell information table 500 (see FIG. 4, hereinafter referred to as NRT 500) configured by information on cells formed in the vicinity of the mobile station 301 (302, hereinafter referred to as the same). Specifically, the NRT storage unit 211 acquires, for example, information on the neighboring cells of the mobile station held by the HeNBs 111 to 113 via the MME 120 and the SGSN 230. The NRT storage unit 211 stores the acquired information.

  The NRT storage unit 211 stores information on neighboring cells of the mobile station 301 in the NRT 500 based on the transition of the mobile station 301 from the LTE system 10 to the 3G system 20. In addition, the NRT storage unit 211 stores a trigger (timing) for deleting information on neighboring cells of the mobile station 301 from the NRT 500.

  The transition from the LTE system 10 to the 3G system 20 is, for example, a Redirection procedure or PS HANDOVER accompanying CSFB from the LTE system 10 to the 3G system 20. In addition, the timing at which the NRT storage unit 211 stores information on neighboring cells is determined after the mobile station 301 transitions from the LTE system 10 to the 3G system 20, before the mobile station 301 transitions to the 3G system 20. It may be either during or after transition. Alternatively, the timing may be when transitioning to the LTE system 10.

  The NRT storage unit 211 stores information on neighboring cells necessary for the mobile station 301 that has fallen back to the 3G system 20 to return from the 3G system 20 to the LTE system 10. Specifically, the NRT storage unit 211 stores frequency information of cells C11 to C13, and information elements (IE) such as PCI or Cell Identity. The information element may include an IE that specifies a wireless communication system (RAT) that temporarily waits for priority, such as a Subscriber Profile ID, and an S1AP Cause.

  Further, the NRT storage unit 211 can include an effective area where application of the effective time of the neighboring cell or the information of the neighboring cell is effective as the information of the neighboring cell.

  “Effective time” is a time during which the neighboring cell is valid as a transition destination candidate. For example, when it is detected that at least one mobile station has accessed the HeNB, 10 minutes from the detection of the access is expected as a time when the mobile station may move to the HeNB again.

  In addition, the “effective area” is a geographical area in which the neighboring cell is selected as a candidate when the mobile station 301 is shifted to another cell. For example, when it is detected that one mobile station has accessed the HeNB, based on the location information of the HeNB, the HeNB that has accessed the NRT 500 of a cell belonging to an area where access to the HeNB is expected The information of is reflected.

  When the mobile station 301 returns from the 3G system 20 to the LTE system 10, the NRT storage unit 211 deletes information on neighboring cells of the mobile station 301 from the NRT 500. Alternatively, the NRT storage unit 211 deletes the information of the neighboring cell of the mobile station 301 from the NRT 500 when a predetermined time (for example, 10 minutes) has elapsed since the information of the neighboring cell of the mobile station 301 was stored in the NRT 500. You can also.

  Further, when the NRT storage unit 211 moves to any one of the predetermined cells (cells C11 to C13 under the LTE system 10), the NRT 500 can erase the information on the neighboring cells of the mobile station 301. That is, the NRT storage unit 211 temporarily stores information on neighboring cells of the mobile station 301 until the mobile station 301 moves to the predetermined cell.

  The mobile station control unit 213 controls the mobility of the mobile station 301. Specifically, the mobile station control unit 213 performs mobility control of the mobile station 301 from the 3G system 20 to the LTE system 10 based on information on neighboring cells stored in the NRT 500. Specifically, the mobile station control unit 213 controls the transition of the mobile station 301 from the LTE system 10 to the 3G system 20 and the transition from the 3G system 20 to the LTE system 10 (including return after fallback). .

  In particular, the mobile station control unit 213 generates control information for returning the mobile station 301 from the 3G system 20 to the LTE system 10 based on information on neighboring cells stored in the NRT 500.

  The notification unit 215 notifies the mobile station 301 and the mobile station 302 of the control information generated based on the neighboring cell information by the mobile station control unit 213 via the BTS 220.

(3) Operation of Radio Communication System Next, the operation of the radio communication system described above will be described with reference to FIGS. FIG. 3 shows a communication sequence of the wireless communication system according to the present embodiment. Here, it is assumed that the mobile station 301 (UE 301) is connected to the LTE system 10 via the HeNB 111.

  In such a state, when there is an incoming voice call to the mobile station 301, the MME 120 notifies the HeNB 111 of CSFB execution to the 3G system 20 triggered by reception of the PAGING signal to the mobile station 301.

  When the CSFB is activated, the HeNB 111 has information necessary for temporarily enabling the return to the HeNB 111 to 113 in the transition procedure (Inter-RAT HANDOVER) to the 3G system 20 (HeNB in the figure). NRT), specifically, the frequency information of the cells C11 to C13 and information elements (IE) such as PCI or Cell Identity are notified to the MME 120. Further, the MME 120 relays the information element to the RNC 210 (Steps S10 to S30).

  The RNC 210 stores the information (HeNB's NRT) relayed by the MME 120 (step S40). In the present embodiment, information that is necessary for realizing the mobility control of the mobile station 301 to the HeNB 111 and that is managed in the HeNB 111, the mobile station 301 needs to transition from the HeNB 111 to the 3G system 20. When the occurrence occurs, the macro cell C1 is notified of the occurrence, and the notified information is temporarily managed by the RNC 210. Thus, by temporarily managing the information in the RNC 210, the processing load associated with the RNC 210 managing the NRT of the HeNB is reduced.

  FIG. 4 shows an example of the NRT 500. As shown in FIG. 4, NRT 500 includes information on neighboring cells (cells C11 to C13) of mobile station 301 relayed from MME 120 in addition to macro cell C1.

  In addition, while the RNC 210 stores the information related to the mobile station 301 relayed by the MME 120 (HeNB's NRT), it can be handled in the same manner as other NRTs. Mobility control such as handover of (mobile station 302) can be executed (steps S50 and S60). That is, the mobile station 302 can transition to the LTE system 10 based on the control (step S70).

  When a predetermined time (for example, 10 minutes) has elapsed since the information of the neighboring cell of the mobile station 301 was stored in the NRT 500, the RNC 210 deletes the information (step S80). As described above, when the mobile station 301 returns to the 3G system 20, the RNC 210 may delete information on neighboring cells of the mobile station from the NRT 500.

(4) Operation / Effect According to the radio communication system according to the present embodiment described above, information on neighboring cells of the mobile station 301 is transmitted to the NRT 500 based on the transition of the mobile station 301 from the LTE system 10 to the 3G system 20. Is memorized. Further, when the mobile station 301 returns to the 3G system 20 (or when a predetermined time has elapsed since the information was stored in the NRT 500), the information on the neighboring cells of the mobile station 301 is deleted from the NRT 500.

  For this reason, even when a large number of base stations exist in the vicinity of the mobile station 301, it is possible to realize the return of the mobile station 301 to the neighboring cells (cells C11 to C13) while suppressing an increase in processing load related to the NRT 500.

  That is, according to the present embodiment, guidance to the cells formed by the HeNBs 111 to 113 can be realized while avoiding the burden of constantly managing the NRTs of the HeNBs 111 to 113 on the 3G system 20 side (RNC 210).

  In the present embodiment, the neighboring cell information may include a valid area in which application of the neighboring cell valid time or neighboring cell information is valid. For this reason, the cell to which the mobile station 301 should return can be controlled more precisely.

(5) Other Embodiments As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. should not do. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  As described above, the CSFB procedure from the LTE system 10 to the 3G system 20 may be Redirection to the 3G system 20 or PS HANDOVER.

  In the embodiment described above, the HeNB 111 notifies the neighboring cell information to the MME 120, and the MME 120 relays the information to the RNC 210. ) May be relayed to the RNC 210 via

  Further, in the above-described embodiment, the RNC 210 stores the NRT 500 and controls the mobility of the mobile station 301. However, the functions of the NRT storage unit 211 and the mobile station control unit 213 may be provided in the MME 120 or the BTS 220.

  Further, the present invention may be applied to mobility control between HeNBs in the LTE system 10, or mobility control between HomeNodeBs (HNBs) and BTSs in the 3G system 20.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

10 ... LTE system
11 ... LTE core network
20… 3G system
21… 3G core network
111-113 ... HeNB
120 ... MME
210 ... RNC
211… NRT storage
213 ... Mobile station controller
215 ... Notification part
220 ... BTS
230 ... SGSN
301,302… Mobile station
500 ... Neighbor cell information table (NRT)

Claims (4)

A network device included in the 3G system for controlling mobility of a mobile station connectable to at least one of an LTE system and a 3G system different from the LTE system,
After the mobile station is determined to transition from the LTE system to the 3G system, before the mobile station transitions to the 3G system, at any time during or after the transition, notification from the LTE system A storage unit that stores information on neighboring cells of the LTE system managed in a base station included in the LTE system, in a neighboring cell information table;
A mobile station control unit that performs mobility control from the 3G system to the LTE system based on the information on the neighboring cells stored in the neighboring cell information table;
When the mobile station returns to the LTE system, the storage unit erases information on the neighboring cell notified from the LTE system from the neighboring cell information table. The network device according to claim 1, wherein the storage unit includes, as the neighboring cell information, at least a valid area in which application of the neighboring cell valid time or the neighboring cell information is valid.   The storage unit erases information on neighboring cells of the mobile station from the neighboring cell information table when a predetermined time has elapsed since storing information on neighboring cells of the mobile station in the neighboring cell information table. 2. The network device according to 1. A mobile station control method in the 3G system for controlling mobility of a mobile station connectable to at least one of an LTE system and a 3G system different from the LTE system,
After the mobile station is determined to transition from the LTE system to the 3G system, before the mobile station transitions to the 3G system, at any time during or after the transition, notification from the LTE system Storing neighboring cell information of the LTE system managed in a base station included in the LTE system in a neighboring cell information table;
Executing mobility control of the mobile station from the 3G system to the LTE system based on the information of the neighbor cell stored in the neighbor cell information table;
And a step of erasing information on the neighboring cell notified from the LTE system from the neighboring cell information table when the mobile station returns to the LTE system.

Images